(1) We will continue our tests of kinetic models which purport to explain the effect of ppGpp and other ribosome inhibitors on the accuracy of translation. (2) We will conduct a critical test of Hopfield's "energy relay" variant of kinetic proofreading in translation. (3) We will attempt to clone the gene for RF2, using the strategem analogous to the one we have used successfully in cloning the gene of RF1. The cloned release factor genes will be used for analysis of the relative contribution of transcriptional and translation error at various positions. They will also be used to map the location of release factor genes in the E. coli genome. (4) We will continue our analysis of the accuracy of transcription. This will involve further studies of an error-prone RNA polymerase mutant we have isolated, and isolation of additional mutants of the same sort. (5) We will extend our computer simulations of cell senescence, and apply the extended computer model to experimental data fibroblast clone size distributions which are being obtained in an associated lab.